TGO Growth on Bond Coats with and without Y Addition

摘要

In order to assess the effect of Y addition on TGO growth, oxidation behavior of MCrAl(M=Ni and/or Co) bond coats with and without 0.5mass.% Y were examined under isothermal condition at 950 to 1100 °C for up to 2000h. The TGO thckness and phase constitution were investigated by means of SEM and EDX, then it was found that TGO formed on Y-free MCrAl bond coats showed slower growth kinetiks than that of fomred on conventional MCrAlY bond coats. The TGO formed on conventional MCrAlY bond coats were composed Al_2O_3 with small amount of Y-rich oxide inclusions. By contrast, Y-free MCrAl coatings formed exclusive Al_2O_3 as the TGO. This result indicates that potential improvements to the bond coat oxidation behaviour can be achieved using Y-free bond coat compositions.